setupIO: simplify code
setupIO: simplify code

There's no need to check err for nil.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

dqminh/runc,opencontainers/runc,opencontainers/runc,kolyshkin/runc,dqminh/runc,dqminh/runc,estesp/runc,estesp/runc,rhatdan/runc,opencontainers/runc,kolyshkin/runc,dqminh/runc,estesp/runc,rhatdan/runc,kolyshkin/runc,rhatdan/runc,opencontainers/runc,kolyshkin/runc,rhatdan/runc